The pattern, timing and rate of enamel development and mineralization (throughout the fetal and post-natal periods) in each type of human deciduous tooth (i.e.: in mandibulary and maxillary incisors, canines and molars) will be determined. The manner in which each tooth develops will first be elucidated to assist in applying the system which has already been divised for enamel sampling and for measuring the rate of enamel development in the deciduous bovine incisors (Deutsch et al, 1979). Having established the general manner of tooth development for each type of tooth, a more detailed examination of labial (buccal) and lingual enamel (under the light microscope, using reflected white light, after imbibing the enamel with chloronaphthalene and, finally, after microradiography) will be carried out, to define the various stages of formation and mineralization. To confirm the impression gained from the appearance of enamel about the various stages of enamel development, particles of enamel dissected serially (tip-cervical margin) from specimens of teeth representing all stages of enamel growth (for each type of tooth) will be analysed chemically for phosphorus, calcium, protein content and amino-acid composition. In this manner, the distribution and composition of mineral and protein along the growing tooth across and within the various stages (zones) of enamel development will be determined. After identifying and defining the different stages (zones) of development that exist in the enamel of each tooth throughout the full spectrum of deciduous enamel growth, the rate at which each stage progresses in the axial dimension (from tip to cervical margin) and the time each stage pesists, will be determined. Having established the pattern of rate of development of enamel in the axial dimension (incisal to cervical), the distribution of calcium, phosphorus and protein from the enamel surface to the dentino-enamel-junction will be determined (at different sites selected along the tooth from tip to cervical margin) in order to characterize the development of enamel in this second dimension). These chemical, physical and morphological studies, and those on the rate and timing of development, will contribute to our detailed understanding of the basic mechanisms by which enamel develops and mineralizes in human decisuous teeth, and could, in the future, provide a better base-line for the understanding of congenital and other enamel defects seen in the deciduous dentition post natally.